Reaction rate: collisions, mechanism and concentration
Reaction rate depends on the microscopic mechanism and can vary with concentrations, temperature and catalysts. Coefficients in the overall equation are generally insufficient to infer the rate law.
Understand before calculating
Reaction rate depends on the microscopic mechanism and can vary with concentrations, temperature and catalysts. Coefficients in the overall equation are generally insufficient to infer the rate law.
Example
Increasing concentration can increase encounter frequency, but the quantitative effect depends on the measured rate law.
The classic trap
Do not turn a model into a literal photograph of reality. Scientific models select particular properties to explain or predict a phenomenon; knowing their limits is part of using them correctly.
Understanding check
Explain the concept to someone who knows the periodic table but not this chapter. Then give one example and one situation where the most common shortcut would become misleading.
Increasing concentration can increase encounter frequency, but the quantitative effect depends on the measured rate law.